实现man.addSleep(1000).eatFood(‘haobao’).addSleep(1000).eatFood(‘gg’)

class LazyMan{
  constructor(){
    this.promise = Promise.resolve()
  }
  addSleep(time){
    this.promise = this.promise.then(()=>{
      return new Promise(resolve=>{
        setTimeout(()=>{
          resolve()
        },time)
      })
    })
    return this
  }
  eatFood(val){
    this.promise = this.promise.then(()=>{
      console.log(val)
    })
    return this
  }
}
let man = new LazyMan()
man.addSleep(1000).eatFood('haobao').addSleep(1000).eatFood('gg')